These type of messages could occur if the attached file timestamps have changed or has been modified.
Assuming you have not modified the file while it was attached, I would suggest that you delete all the result cases associated with the attached file. Then try to detach the file.
See if you are able to detach the file without these messages.
You also may want to try to use the later version of patran possibly 2017 and see if you are able to avoid this issue.